Cheetahs: Critically endangered and genetically impoverished

cheetahs

Cheetah family in the Masai Mara. © GP232/ iStock

Cheetahs are among the fastest sprinters in the animal kingdom, but they can’t outrun this threat: a new study reveals that these already severely depleted big cats are also genetically impoverished. Together with the snow leopards, they show the lowest heterogeneity and the strongest signs of inbreeding. This underscores the high level of endangerment facing cheetahs and the urgency of better protection for this cat species, the researchers said.

Apex predators such as the cheetah play an important role in their ecosystems. Because they regulate the stock and balance of the level of the food chain below them. When these top predators decline because their habitat is shrinking and they are heavily hunted, the entire ecosystem is impacted.

Distribution area and stock shrunk greatly

This is exactly the case with the cheetah (Acinonyx jubatus): The populations of this big cat have shrunk dramatically. “At the end of the 19th century, the range of cheetahs still included most of the regions of Africa not covered by rainforest and a large part of western and southern Asia – from the Arabian Peninsula to India and in the north to Kazakhstan,” explains Stefan Prost from the veterinary department University of Vienna and his colleagues. Today, the cheetah is found in only nine percent of its former habitat.

Threatened by habitat loss, human-wildlife conflict and illegal trade, only about 7,100 cheetahs remain in the wild. The cheetah is one of the endangered mammal species, and individual subspecies are even threatened with extinction. Most of the wild cheetahs belong to a large population in southern Africa, which is also considered a separate subspecies – Acinonyx jubatus jubatus. Significantly fewer animals belong to the remaining four subspecies. The populations of Aj hecki in Northwest Africa and Aj venaticus in Iran – the last representatives of the Asian cheetahs – are considered to be particularly threatened.

Five subspecies – two of them critically endangered

To find out more about the consequences of the population decline and the relationships between the subspecies, Prost and his colleagues analyzed DNA samples from cheetahs from almost the entire current and former range. It was initially shown that the cheetah genomes form five clusters – corresponding to the four recognized subspecies and a fifth, previously disputed. “We found strong genetic differentiation between all of the classically recognized subspecies, disproving previous assumptions that cheetahs show little differentiation,” reports Prost’s colleague Pamela Burger.

At the same time, the genetic analyzes confirmed that East African cheetahs (A. j. raineyi) differ genetically from South African individuals (A. j. jubatus). “Knowing about the subspecies in cheetahs is important for their conservation, because the distribution often serves as a basis,” the researchers explain. This is particularly relevant given ongoing and planned translocations of cheetahs across subspecies boundaries. So far, cheetahs have been brought from southern Africa to East Africa to increase the population there. But if both belong to different subspecies, this further threatens the survival of the already critically endangered smaller subspecies in East Africa.

Clear evidence of inbreeding

In addition, the genetic diversity has already decreased significantly due to the sharp decline in the cheetah population. In the critically endangered Iranian and Northwest African subspecies A. j. venaticus and A.j. hecki, Prost and his colleagues found only very low heterozygosity. This is an indication of high inbreeding in these populations. “Together with snow leopards, cheetahs have the lowest genome-wide heterozygosity of all big cats,” reports Prost. “This underscores the critical conservation status of the cheetah.”

Source: University of Veterinary Medicine, Vienna; Article: Molecular Ecology, doi: 10.1111/mec.16577

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